The present invention relates to a variable displacement compressor.
A vehicle air conditioner includes a compressor for compressing refrigerant. One type of compressor is driven by an engine and an electric motor. Japanese Laid-Open Patent Publication No. 2002-81375 describes such a compressor.
The compressor includes a housing that accommodates a compression mechanism. The housing supports the end portions of a rotary shaft in a rotatable manner. The end portions of the rotary shaft project from the compressor. The rotary shaft is used to drive the compression mechanism. A pulley connects one of the end portions projecting from the compressor to the engine. The other one of the end portions projecting from the compressor is connected to the electric motor, which is arranged outside the compressor.
Such a compressor that is connected to an electric motor arranged outside the compressor may be made more compact than a compressor that houses the electric motor therein. Further, the housing, which accommodates the compression mechanism, and the electric motor may be assembled separately and then connected to each other. This facilitates maintenance and replacement of the electric motor.
To hermetically seal the housing, seals must be arranged between the housing and the two end portions of the rotary shaft. It is preferable that the seals be lubricated and cooled to reduce friction between the seals and the rotary shaft and to improve the durability of the seals.
As known in the prior art, a seal may be arranged along a circulation path of the refrigerant in the housing to improve lubrication and cooling. However, the known compressors with seals arranged along the circulation path do not employ rotary shafts having both of their end portions projecting from the compressor. That is, in the prior art, in a compressor having a rotary shaft with only one end portion projecting from the compressor, only the projecting end portion is sealed. However, for a compressor having a rotary shaft with both of its end portions projecting from the compressor, there are no known structures that seal both end portions. Accordingly, there is a demand for a compressor that efficiently lubricates and cools the seals arranged on both projecting end portions of the rotary shaft.